> You can have a contract without much property, and a contract can> agree to pretty much any arrangement imaginable, including ones> without any property. So contracts seem more general.

It's much more fundamental than that: property *is* merely a contract,
albeit usually unwritten. In the greater scheme of things nobody "owns"
anything, but in our small-town grubbing about in the dirt, property is
seen as a useful accommodation (ie. a contract) between people at a time
of constrained resources. It won't last though. Tomorrow, if you want
my estate, world, or galaxy, I'll give it to you, perplexed at why you
should have such an odd affectation.